In his new 802-page masterwork, The Better Angels of Our Nature: Why Violence Has Declined, the bestselling author and two-time honoree on TIME 100 list of the most influential people in the world makes a nearly ironclad case for human progress toward peacefulness.

I recently spoke with Pinker about his book and the critical influences that can pacify the human brain.

TIME: What’s the most compelling evidence that violence has genuinely declined over the course of history?

PINKER:I guess what struck me first was the 35-fold decline of homicide in Europe since the Middle Ages. Various countries of Europe have kept homicide statistics since the Middle Ages and it’s a curve that plummets downward. So, quantitatively, that would be the most dramatic. Qualitatively, I think it would have to be the [shift in public opinion regarding] various forms of criminal punishment since the Middle Ages, such as disemboweling, impalement, breaking on the wheel. That played out until the early modern period, until the Enlightenment, the second half of the 18th century.

The gruesome and infinitely creative forms of tormenting someone for as long as possible, in as painful and as humiliating a manner as possible — that the human mind could even come up with these torments makes me ashamed of being a member of Homo sapiens. The fact that I have this reaction today, whereas at the time, it was fun for the whole family — people would come out to jeer and laugh and watch the doomed prisoner struggle and scream in agony — that difference I think would be the most dramatic and qualitative example of the decline in violence.

What about the Holocaust? Some say the 20th century was the bloodiest time ever. How can you say that things are getting better?

It’s confusing a data point with a trend. The idea that the Holocaust was a terrible event is certainly true. But what’s not true is that this was a sign of things getting worse and worse. For one thing, before the 20th century, there were plenty of genocides. We tend to forget about them, partly because they weren’t as well documented and partly because until recently, people didn’t care. We used euphemisms like sackings and sieges instead of calling them genocides.

It’s not true that the 20th century saw the origin of genocide. Of course, genocides didn’t end in 1950. There were genocides in China, Cambodia, Rwanda and Darfur. Still the trend is not upward. The trend is downward. Especially when calculated as a portion of the world’s population. The rate of death in genocide has come down since the peak in the 1940s.

According to a theory that I cite by Norbert Elias, the German sociologist, the decline of violence in Europe went hand in hand with the change in manners. We know from cultural history that what we now consider dignified manners developed gradually in Europe in the transition from the Middle Ages to modernity.

Elias suggested that there was a causal relationship. Mainly that when you wait for everyone to sit down before falling on the carcass in the middle of the table, when you remember to chew with your mouth closed and not to gnaw on a bone and put it back in the serving dish, not to slurp soup out of your saucer, all of this general habit of cultivating delay of gratification and self-control spills over into control of impulsive violence. So, you’re less likely, he argued, to respond to an insult with violent outburst.

You see this in terms of gradually training the “higher” parts of the brain to exert more self-control over impulses.

Psychologist Roy Baumeister showed that when people’s self-control has been temporarily fatigued by having to resist a temptation they’re weaker at resisting further temptations. In fact at least in the weak forms of violence you can study in the lab, they’re more likely to commit acts of violence. Also you can train up the self-control, almost as if it’s a muscle that is being strengthened. If it’s trained in one domain of life, it generalizes to another.

Students, for example, who inhibit the habit of swearing in every sentence, or who make an effort to speak in complete sentences, also lose weight, study more, put away the dishes and show other forms of discipline in their lives.